The present invention relates to a semiconductor laser module of the dual in-line package type suited to be used as a transmitting light source of a high-speed transmission system having a transmission rate of 1 Gb/sec or more.
In a conventional semiconductor laser module of the dual in-line package type, as described in a Japanese patent application JP-A-61-200,514 and the NEC technical Report (Vol. 38, No. 2, 1985, pages 84 through 89), an input terminal connected to a semiconductor laser is formed of one of airtight terminals of the dual in-line type. Such a structure is advantageous in that the semiconductor laser module can be readily mounted on a printed board or the like, but has a drawback that it is difficult to make short the length of the input terminal. Accordingly, the radiation leakage of a high-frequency signal is generated at the input terminal, and thus the frequency of an input signal applied to the semiconductor laser is limited. In other words, the conventional semiconductor laser module of the dual in-line package type pays no attention to the connection of the input terminal to a drive circuit which generates a high-frequency signal in the order of 1 Gb/sec (that is, in the giga bit band). Accordingly, the operation of the semiconductor laser module is not satisfactory in the giga bit band.